Facebook announced today that it sold $100,000 worth of ads to a sketchy network of fake Russian accounts between June 2015 to May 2017, a period spanning the 2016 election cycle. The ads often mentioned particular political issues, like LGBT rights or gun control, but rarely mentioned a specific political candidate or the US presidential election.

“One question that has emerged is whether there’s a connection between the Russian efforts and ads purchased on Facebook,” Alex Stamos, the company’s chief security officer, said in a statement. “These are serious claims and we’ve been reviewing a range of activity on our platform to help understand what happened.”

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Facebook says the ad buys came from 470 “inauthentic” accounts and pages that seemed affiliated with each other and appeared to be operating from Russia. The social network shut down the accounts and pages that remained active for violating its policies.

Since the election, Facebook has been reviewing its role in spreading disinformation. In April, it published a comprehensive review of coordinated disinformation campaigns on its platform, noting that such campaigns often focused on spreading confusing or promoting specific causes. Facebook doesn’t say why it reviewed ad purchases in particular, but it sounds like the review may have stemmed from its broader investigation into disinformation campaigns.

Representatives from the company explained the findings to congressional investigators today and noted that the accounts associated with the ad buys could be traced to a Russian troll farm, The Washington Post reported.

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Only a quarter of the ads were targeted geographically, and most of those ads ran in 2015, Facebook said. The ads focused on “amplifying divisive social and political messages across the ideological spectrum” and used techniques Facebook previously identified as those used by disinformation campaigns, Stamos said.

Facebook conducted a broad review of ads on its platform, looking for ad buys that might have even a loose connection to Russia. “This was a broad search, including, for instance, ads bought from accounts with US IP addresses but with the language set to Russian — even though they didn’t necessarily violate any policy or law,” Stamos said. This broader review uncovered $50,000 spent on ads with political content.

Gizmodo contacted Facebook for more information about the ad buys and will update if we hear back.